How to check the operation of marine bearings

Large machinery cannot be rotated manually, so the power shall be cut off immediately after no-load startup, and the machinery shall be idled. Check whether there is vibration, noise, contact of rotating parts, etc., and enter into power operation after confirming that there is no abnormality. Power operation starts from no-load low speed and slowly increases to the rated operation under the specified conditions. During the test run, check whether there is abnormal sound, change of bearing temperature, leakage or discoloration of lubricant, etc. If any abnormality is found, the operation shall be stopped immediately, the machinery shall be inspected, and the bearing shall be removed for inspection if necessary.

Maintenance, repair and troubleshooting

1. In order to keep the original performance of rolling bearing and use it in good condition for a long time, it is necessary to check and maintain the bearing regularly to prevent faults, ensure reliable operation and improve efficiency and benefit.

2. Regular maintenance shall be carried out according to the operation conditions and operation standards of the machine. The contents include monitoring the operation status, replenishing or replacing the lubricant for the marine bearing, and regular disassembly and inspection.

3. The maintenance items in operation include the rotating sound, vibration, temperature and lubricant state of the bearing, etc.

4. Find out the abnormal state during operation, find out the cause and take corresponding countermeasures. Carefully inspect the removed bearing as required.

5. Maintenance of bearings after disassembly.

The bearing temperature can generally be inferred from the external temperature of the bearing seat. However, it is more accurate to measure the temperature of the outer ring of the bearing directly by using the oil hole. The temperature of the bearing rises gradually from the beginning of operation, and it is usually stable after 1-2 hours. If the bearing is not installed properly, the temperature will rise sharply and abnormal high temperature will occur. The reasons include too much lubricant, too small bearing clearance, poor installation, too much friction of sealing device, etc. In the case of high-speed rotation, the wrong choice of bearing structure and lubrication mode is also the reason. The rotating sound of the bearing was examined by stethoscope, which showed that there was strong metal noise, abnormal sound and irregular sound. The reasons include poor lubrication, poor accuracy of shaft or bearing seat, damage of bearing, invasion of foreign matters, etc.

Generally speaking, the correct use of bearings can achieve fatigue life. However, in case of accidental early damage, it cannot be used again. Unlike fatigue life, this early damage is called a failure or accident. Most of them are due to improper consideration of installation, use and lubrication, foreign matters invading from the outside or insufficient research on the shaft and bearing seat, etc. The damage state of the bearing, such as the abrasion of the retaining edge of the ring of the roller bearing, may be caused by insufficient lubricant, inappropriate brand, defective oil supply and drainage structure, invasion of foreign matters, bearing installation error or excessive deflection of the shaft, or by a combination of the above reasons. Therefore, it is difficult to know the real cause of the damage only by investigating the bearing damage. However, if, on the basis of fully understanding the machine, working condition and peripheral structure of the bearing, the situation before and after the occurrence of the fault is made clear, and then combined with the damage of the bearing and a variety of related reasons for analysis, the same kind of fault can be prevented again. Table 3 shows the typical causes and Countermeasures of bearing damage.